|Abdi, Reta - UNIVERSITY OF TENNESSEE|
|Aregawi, Weldegebrial - ETHIOPIAN INSTITUTE OF AGRICULTURAL RESEARCH|
|Bekana, Merga - ADDIS ABABA UNIVERSITY|
|Van Leeuwen, Thomas - GHENT UNIVERSITY|
|Delespaux, Vincent - VRIJE UNIVERSITY|
|Duchateau, Luc - GHENT UNIVERSITY|
Submitted to: BMC Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2017
Publication Date: 4/13/2017
Publication URL: http://handle.nal.usda.gov/10113/5700732
Citation: Abdi, R.D., Agga, G.E., Aregawi, W.G., Bekana, M., Van Leeuwen, T., Delespaux, V., Duchateau, L. 2017. A systematic review and meta-analysis of trypanosome prevalence in tsetse flies. BMC Veterinary Research. 13:100. doi:10.1186/s12917-017-1012-9.
Interpretive Summary: Trypanosomes are parasites that cause sleeping sickness in humans and gradual emaciation and weakness in cattle. They are transmitted as a result of a bite from tsetse flies. Parasitic load in the tsetse fly determines the degree of transmission of the parasite by the vector. This will indirectly aid to optimize control measures. Systematic reviews and meta-analyses are statistical methods that are used to combine results from several studies for more powerful conclusions. Systematic review of previously published studies documenting trypanosome infection in the tsetse flies from field surveys or from laboratory experiments were conducted. Performance of various methods for the detection of trypanosomes in the tsetse flies was also investigated. Microscopic examination of the flies was the most widely used method to detect trypanosomes. Our combined analysis indicated that the infection rate in the tsetse flies was about 10% under field studies, and 31% under laboratory experiments respectively. Infection rates in the tsetse flies varied by country and the year of publication. The performance of other methods used for the detection of trypanosomes in the tsetse flies was poor in comparison to microscopic examination. Our study indicated the need for improved technologies for the detection of trypanosome infections in the tsetse flies.
Technical Abstract: Background: The optimisation of trypanosomosis control programs warrants a good knowledge of the main vector of animal and human trypanosomes in sub-Saharan Africa, the tsetse fly. An important aspect of the tsetse fly population is its trypanosome infection prevalence, as it determines the intensity of the transmission of the parasite by the vector. We therefore conducted a systematic review of published studies documenting trypanosome infection prevalence from field surveys or from laboratory experiments under controlled conditions. The microscopic examination of dissected flies (dissection method) remains the most used method to detect trypanosomes and thus constituted the main focus of this analysis. Meta-regression was performed to identify factors responsible for high trypanosome prevalence in the vectors and a random effects meta-analysis was used to report the sensitivity of molecular and serological tests using the dissection method as gold standard. Results: The overall pooled prevalence was 10.3% (95% confidence interval [CI] = 8.1%, 12.4%) and 31.0% (95% CI = 20.0%, 42.0%)for the field survey and laboratory experiment data respectively. The country and the year of publication were found to be significantly associated with the prevalence of trypanosome infection in tsetse flies. The alternative diagnostic tools applied to dissection positive samples were characterized by low sensitivity, and no information on the specificity was available at all. Conclusion: Both temporal and spatial variation in trypanosome infection prevalence of field collected tsetse flies exists, but further investigation on real risk factors is needed how this variation can be explained. Improving the sensitivity and determining the specificity of these alternative diagnostic tools should be a priority and will allow to estimate the prevalence of trypanosome infection in tsetse flies in high-throughput.